Electronic devices or integrated circuit devices, such as, for example, processing devices or memory devices, are used in a variety of technical fields and may, for example, be used in safety critical systems, for example in automotive safety critical systems, where failure or malfunction of the device may result in damage or dangerous situations for a user of the safety critical system, e.g. a car driver. In order to specify functional safety, for example, for automotive applications, functional safety standards are defined, for example the ISO 26262 functional safety standard by the International Organization for Standardization (ISO) or the IEC 61508 standard by the International Electrotechnical Commission (IEC). For example, ISO 26262 defines levels of failure risk reduction wherein, for example, acceptable process safety times according to certain safety integrity levels (SIL) are defined. Process safety times are periods of time wherein a very low probability of failure of the integrated circuit device can be expected.
Functional safety of an integrated circuit device may, for example, be tested using built-in self test (BIST) circuitry implemented as part of the integrated circuit device together with the application circuitry and associated with the application circuitry such that internal functional units of the application circuit become accessible for test patterns during a built-in self test. Circuits such as flip-flop circuits may, for example, be connected to form a long shift register or scan chain, through which a test pattern may be loaded into the integrated circuit in order to put the integrated circuit in a defined test state. After performing a test of at least one clock cycle duration a test result pattern, i.e. a resulting signature bit sequence may be received from the integrated circuit through the scan chain. In case of correct functioning of the device, the received signature is identical to an expected signature. A self test of an integrated circuit device is often performed during an initialization or power up period, and/or during a shutdown or power down period of the device or sometimes during run time of the device, i.e., during being powered on.